Due to the greenhouse effect, life-threatening temperatures can develop very rapidly inside the passenger cabin of a parked motor vehicle when ambient temperatures exceed 75° F. Animals and small children confined in a car with the windows closed will succumb to heat exhaustion in a matter of minutes as the cabin temperature exceeds 110° F. Deaths of children and pets from heat exposure in parked vehicles are recurring tragedies that can be avoided with suitable prevention systems. The development of advanced central microprocessor systems capable of monitoring and controlling all vehicle systems in newer vehicles provides a means by which cabin temperatures can be monitored and maintained within a safe range.
The need to respond rapidly to cabin over-heating in an occupied parked vehicle must be balanced, however, with the need to preserve the security of the occupants, who are often infants and pets. For example, immediately opening windows and unlocking doors when a temperature increase is detected may leave an infant exposed to abduction or enable a pet to escape. Therefore, there is a need for a system which implements a graduated, progressive series of warnings and responses as the cabin temperature reaches certain designated setpoints, so that security-compromising steps can be deferred until less extreme measures have been exhausted.